The letter reads: “In October you [the magazine] had a star letter in the mailbag pages which was a very useful piece of information.

“It explained how our families can purchase a local Skype number for us to call our families who are abroad.

“The international call rates cost a lot using the prison PIN system and the Skype option looked like a perfect solution. The best part was that it was legal and no breach of prison rules as the call was made to a direct number and was not being redirected. But when I recently tried making my first call I was told by staff here at HMP Frankland that I am not allowed to make any calls through Skype.

“I tried to explain that according to Inside Time it had been allowed in other prisons but the response was a firm ‘No’ as HMP Frankland is part of the high security estate.”

Karim appealed against his sen arguing his plans were unlikely to come to fruition, but Appeal Court judge dismissed the case.

John Roberts, for Inside Time, said: “We should...be interested in anything that helps prisoners communicate on a regular basis.

“Bearing in mind prisoners earn on average only £12 per week the cost of telephone calls for them are proportionately much higher than they are for everyone else. I have never heard of any logical reason not to allow Skype.”

A Prison Service spokesperson said: “Prisoners are only allowed controlled access to the internet in exceptional circumstances, but do have access to a phone to keep in contact with family and friends. Calls are recorded and monitored, can only be made to approved numbers, and must be paid for by the prisoner.”